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Abstract #0807

Dynamic Manganese-Enhanced MRI Reveals Dominant Modulation of Myocardial L-Type Calcium Channel Flux by Neuronal, Not Endothelial Nitric Oxide Synthase in Mice

Moriel H. Vandsburger1, Brent A. French1,2, Christopher M. Kramer2,3, Frederick H. Epstein1,2

1Biomedical Engineering, University of Virginia, Charlottesville, VA, USA; 2Radiology, University of Virginia, Charlottesville, VA, USA; 3Medicine, University of Virginia, Charlottesville, VA, USA

Modulation of L-Type Calcium Channel (LTCC) flux plays an important role in calcium cycling and cardiomyocyte contractility. Manganese (Mn2+) enters cardiomyocytes through the LTCC and shorterns T1 proportionatly. Modulation of LTCC flux by neuronal (nNOS) and endothelial (eNOS) isoforms of nitric oxide synthase is unclear. The uptake of Mn2+ was examined in wild type (WT), nNOS-/-, and eNOS-/- mice at baseline and with dobutamine using an ECG-gated saturation recovery pulse sequence with constant repetition time (TR) of 200ms. Whereas baseline LTCC flux was higher in nNOS-/- mice and unchanged with dobutamine, LTCCI increased with dobutamine in WT and eNOS-/- mice.